With Dual-Mode Wireless Charging IC, IDT Urges to Cut the Cords

Wireless charging technology is technically challenging, requiring advanced mixed-signal architecture, according to IDT's CEO. "Our competitors are trying to catch up but are still failing," he said.

What makes it so difficult?
The big problem is that, even when using the inductive coupling principle, different appliances have different range and power requirements. The solution is a variable frequency solution, explained IDT's Naghavi. He explained that devices based on WPC or PMA specs use variable frequencies ranging between 100kHz to 200kHz or 300kHz, requiring different load and power.

IDT's engineering team, led by Naghavi, came up with architecture -- integrated with a microcontroller -- that can modify itself through firmware.

Integrated into IDT's dual-mode receiver chip are a high-efficiency synchronous full bridge rectifier, high-efficiency synchronous buck converter, and control circuits to wirelessly receive an AC power signal from a compatible transmitter and convert it into a regulated 5V output voltage for powering and charging portal electronics, according to the company. The device delivers 5W in WPC and PMA modes in accordance with those standards. When paired with IDT wireless power transmitters, systems can make use of the proprietary power control loop embedded in the communication protocol to achieve a 50 percent increase in output power to 7.5W, IDT claimed.

Will there be a solution in the offing that can support not just magnetic induction technology such as WPC and PMA, but also the magnetic resonance technology-based A4WP spec? Although magnetic resonance uses a very high frequency -- such as 6.78MHz -- compared to magnetic induction, the principle of supporting variable frequency remains, requiring a rectifier based on frequency, Naghavi explained.

IDT has been working on wireless charging technology for two and a half years, said Naghavi. Seeking to develop a single architecture that can be modified through firmware, Naghavi went to a potential customer and boldly vowed: "We will make our solution dual-mode and we will do it on a single chip." At the time, IDT's competitors, such as Texas Instruments, were struggling to find a stable solution, using eight chips. A year later, when Naghavi showed up with the promised sample, "the customer told me two words -- "wow" and "congratulations," according to Naghavi. The customer told him: "A year ago, I thought you were crazy."

No one knows yet how quickly a wireless charging infrastructure will build up. Cellular operators are serious about wireless charging, because they want to send specific advertisements -- such as "muffins are on sale today" -- to mobile phones placed at charging stations at coffee shops, fast food joints or airports, explained McCreary.

Less clear is the wireless charging market for the home, he noted. "There is a cool factor" to wireless charging, noted McCreary, but it might be trumped by practicality. After all, most homes have plenty of handy power plugs.

Samsung offers for its smartphone a wireless charging cover as an accessory.

This sounds like "much ado about nothing". If I'm near enough to the charging pad to charge my phone, I might as well plug in my USB cord and recharge at the end of my meter long leash (power cord). It gives me more flexibiloity than trying to talk on the phone or surf the web while the phone rests on the charging plate. As a frequent traveler, I see the cluster of people on their phones at the power outlets, I don't see a benefit of having to get even closer to use the recharging plate.

I certainly understand some people would feel that way, DrQuine. But then, when I'd have to compete for precious power outlets at the airport (and there aren't a lot of them around), I do long for wireless charging pad.

Hi Bert, the Shakespearian allusion not withstanding, there are many cases that warrant wireless charging, some as Junko mentioned are handy when you are travelling or in places where more clients need charging outlets than are available. Or in cases where you are missing any charging cables!

But I agree with your point on efficiency and further wastage of energy. Efficiency is the key to limit such wastages. Couple of years ago I saw a presentation on Capacitive charging where 83% efficiency was demonstrated over a 6x10mm area at 0.5mm separation.

It is much ado about nothing, IF you have a nice benign environment. Make it nasty like the stuff military hardware has to endure, and then an environmentally sealed charging method suddenly looks very attractive from a reliability stand point. Connectors are the number one failure mode of almost anything electronic. Period.

If you want to see resonant proximity charging on a much larger scale, surf on over to http://www.witricity.com and see power transfer into the low kW range for EV's. We are currently working with WiTricity on an adaptation of their system for an autonomous military system in a harsh environment.

As this technology matures, it will become much more prevalent. Consumers will pay for convenience. They always have and always will.

I don't think people will travel with their charging pad, but they will still travel with their charger, so unless the airport provides the infrastructure (as in pads), I don't see your argument. I see charging pads as mainly a home or work convenience. The difference in cost between an outlet with an extension cord and a pad (that still needs an outlet) is huge. Coupled with the limited number of devices a single pad can support, I'm not sure many places will spend that capital. Except Starbucks ...

Of course, if you talk about the difference in cost between an outlet with an extension cord and a pad, the argument for using wireless charging at home loses. But when your smartphone battery barely lasts for a day, you do sometimes wish if you could "tap it off" -- just in a few minutes -- some place in public so that you can call someone.

How about in your car? Get in your car, put the phone in its cradle (with inductive charger), and drive. You can ask your phone for the nearest steakhouse, and listen to an mp3 fille, sent to your car stereo over Bluetooth.

Having to plug and unplug in the micro-USB charger every time you get in/out of the car gets very annoying after a while so most people wouldn't bother most of the time.

One of the things that convinced me that this might take off was cellular operators' interest and their involvement in wireless charging.

With the backing of the cellular operators (who obviously want to know where your phones are placed -- beyond the information your phone's GPS is giving out), this will happen over time. (if no operators are interested, infrastructure buildout is unlikely to happen.)

More importantly, once operators say that this is something they want, handset vendors jump; and chip companies need to supply solutions. And consumers will be gladly to accept. After all, who wants to carry a power cord with your phone?